Mercury sphygmomanometers



Feb- 7, 1967 P. P. PARERA ETAL 3,302,638

MERCURY SPHYGMOMANOMETERS Filed Sept. 20, 1963 24 -sEM/-F/L rf@ 1 23,cm/P85555 AIR United States Patent Office 3,32,638 Patented Feb. 7,1967 4 Claims. (cl. 12s- 2.05)

The present invention refers to improvements in or relating to mercurysphygmomanometers, and more particularly to an apparatus for measuringarterial tension.

An important object of the present invention is to provide asphygmomanometer of such dimensions as to be readily carried on thephysicians person vand which in use assures an easy and accuratereading.

To accomplish the above and other -objects and advantages, the inventioncomprises a housing constituting a compression chamber having in itsbase a mercury supply, a measuring tube located within the housing andtapering upwardly from its lower end which is in communication with themercury supply, With the upper end of the tube being provided with asemi-filter through which the tube communicates with the interior of thecompression chamber, an inlet for the housing in communication with themercury supply and with a compressor armlet via a suitable connectionsuch las a hose, a semi-filter located within the inlet, ia furtherinlet in the housing communicating with the interior of the tube at aposition slightly above the zero level of the mercury column and asemi-filter positioned in the latter inlet with such latter inletserving to equalize the atmospheric pressure with that of the interiorof the tube and the compression chamber for obtaining absolute precisionin the measurement `of the arterial tension.

Further objects and advantages of Ithe invention will become morereadily apparent from the ensuing detailed description and annexeddrawings, and in which drawings:

FIGURE 1 is a vertical sectional view of an apparatus embodying thepresent invention, and

FIGURE 2 is an elevational view on a reduced scale of the apparatusshown in FIGURE 1.

FIGURES 1 and 2 show a manometer upwardly tapered tube 15 which d-ue toits form regularizes the manometric scale, reducing it and making itproportional. The lower part of the tube 15 is introduced in a syphonfashion within la mercury receptacle 16.

The upper part of the tube 15 carries a semi-filter 17 which functionsas a stopper for the tube. A housing 18 surrounds the tube and forms thecompression chamber which embraces the full length of the tube. Hence,the chamber is of the same length as the tube or centimeters, thusreducing the size of the apparatus to a minimum.

A cylindrical lens or prism 19 having Ia scale thereon is placed at thefront or inside the compression chamber -to facilitate the reading ofthe mercury column.

The base of the housing serves as a mercury receptacle 20 which is`completely filled without a single air bubble and which onlycommunicates with 4the exterior through an inlet 21 in which a semilter22 is placed to avoid spilling of the mercury exteriorly of theapparatus.

A fitting 23 is provided for the inlet 21 and the tting is incommunication with a compressor armlet (not shown) by way of a flexibleconduit such asa tube associated with the fitting.

Upon injecting compressed yair through the fitting 23 related to theinlet 21, the mercury rises in the tapered tube 15 indicating thepressure and forces the air situated -above the mercury column throughthe semiiilter 17 towards the compression chamber 18 in which the airpossesses similar characteristics to those of ambient conditions due tothe fact that prior to using the apparatus, the interior of the chamberwas placed in communication with the ambient atmosphere through asemifilter 24 the mouthpiece of which is obstructed by the mercury whenthe latter rises in the manometric tube 15.

The dimensions of the casing holding the various components of theapparatus are approximately x 112 X 3() mm.

It will be appreciated that by virtue of the upwardly tapering manometertube 15 the capacity thereof will assure a perfect reading since, bydiminishing the section of the tube in the upward direction, the columnof mercury will likewise be reduced in volume :and in Weight. Since theheight attained in a manometer tube when closed is a function of itsdiameter and thus in direct relation to its section, provided thetemperature and volume of the compression chamber 18 remains constant,the tube and chamber function in the form of a balance, so to speak,with the pressure required to be measured being exerted at the entranceto the tube and the opposing compression from the compression chamberbeing exerted on the other end of the tube and to which lat- -terpressure is added the weight of the rising column of mercury. Hence, ifone of the values is maintained constant the height obtained by themercury column at the same exterior pressure will 'be in inverserelation to the section of the mercury column. The graduation of thecolumn will be closer the higher the point of measurement or, whenapproaching 300 mm. of mercury, there can `be obtained a completelyregularly marked scale.

By reason of the inlet and semi-filter 24 it is possible to equalize theinternal and ambient pressures and such inlet is closed upon the risingof the mercury column.

The invention is not to be confined to any strict conformity to theshowings in the drawings but changes or modifications may be madetherein so long as such changes or modifications mark no materialdeparture from the spirit and scope of the appended claims.

What we claim is:

1. An ,apparatus for measuring `arterial tension comprising a housingconstituting a compression cham-ber and having upper and lower ends, amercury supply in the lower end of the housing, an upwardly taperingtube having upper and Ilower ends within the compression chambercommunicating at its lower end with the mercury supply and at its upperend to the compression chamber, and a semi-filter yclosure meanscommunicating exteriorly of the housing and with the interior of thetube in proximity to the zero level of the mercury column in the tube.

2. The apparatus for measuring arterial tension as References Cited bythe Examiner in claim 1 in which said housing and tube are UNITED STATESPATENTS 3. The apparatus for measuring arterial tension as 16717859/1875 Pond 128`2-05 claimed in claim 1 including a semilter c-losuremeans 5 1,245,559 11/1917 Booth 12S-'205 X for the upper end of the tubeconstituting a fluid im- 21669125 2/1954 Hesse 73-402 perviousconnection between the compression chamber FOREIGN PATENTS and theinterior `of the tube.

4. The apparatus for measuring larterial tension as claimed in claim 3including an inlet communicating With 10 RICHARD A G AUDET primaExaminer the mercury supply and With a compression armlet, reryspectively, and a semi-filter located in said inlet. SIMONBRODEKEXHMIIQI'.

1,192,165 4/1959 France.

1. AN APPARATUS FOR MEASURING ARTERIAL TENSION COMPRISING A HOUSINGCONSTITUTING A COMPRESSION CHAMBER AND HAVING UPPER AND LOWER ENDS, AMERCURY SUPPLY IN THE LOWER END OF THE HOUSING, AN UPWARDLY TAPERINGTUBE HAVING UPPER AND LOWER ENDS WITHIN THE COMPRESSION CHAMBERCOMMUNICATING AT ITS LOWER END WITH THE MERCURY SUPPLY AND AT ITS UPPEREND TO THE COMPRESSION CHAMBER, AND A SEMI-FILTER CLOSURE MEANSCOMMUNICATING EXTERIORLY OF THE